GRE Test. Tips?

Here's another one:

Tanks X and Y are filled to capacity with
fucl. Tank X holds 600 gallons more than Tank Y.
If 100 gallons of fuel are to be pumped into each
tank, tank X would then contain 3 times as much
fuel as tank y. What is the total number of gallons
of fuel in thc two full tanks?

OK the answer I got is B)1200.

x holds 600 more = 800 if y holds 200

add 100 to each 900 + 300 = 1200. Right?

BUT, checking the answer is A)1400

Number crunching, I cant figure out an equation which holds 600 more and 3 times after adding 100 to equal 1400.

Even if I missed something, both answers would be right.

Questions like this one piss me off because you easily figure it out and then find it was wrong. Doubts creep in for the rest of the questions

As @darth has mentioned, you do not need to add the final (100+100) to get your total number as that was a hypothetical situation.

Going back to basic algebra:

X=Y+600 ... (1)

X+100 = 3Y+300 ... (2) [If 100 were pumped into that is added]

(2) - (1) => 100 = 2Y -300 => Y=200=> X= 800

So total should be 200+800 = 1000.

As a double check: when you add 100 to each: Y would contain 300 and X would contain 900, which is 3 times 300.

Now if the question meant it was pumped OUT... then

X=Y+600 ... (1)

X-100 = 3Y-300 ... (2)

(2) -(1) => Y=400 => X=1000 hence total = 1400. Bingo!
 
As @darth has mentioned, you do not need to add the final (100+100) to get your total number as that was a hypothetical situation.

Going back to basic algebra:

X=Y+600 ... (1)

X+100 = 3Y+300 ... (2)

(2) - (1) => 100 = 2Y -300 => Y=200=> X= 800

So total should be 200+800 = 1000.

As a double check: when you add 100 to each: Y would contain 300 and X would contain 900, which is 3 times 300.

I am not sure where you got 1400 to be the correct answer tho... please double check...

Read previous few posts .. Question was misread :)
 
As @darth has mentioned, you do not need to add the final (100+100) to get your total number as that was a hypothetical situation.

Going back to basic algebra:

X=Y+600 ... (1)

X+100 = 3Y+300 ... (2)

(2) - (1) => 100 = 2Y -300 => Y=200=> X= 800

So total should be 200+800 = 1000.

As a double check: when you add 100 to each: Y would contain 300 and X would contain 900, which is 3 times 300.

I am not sure where you got 1400 to be the correct answer tho... please double check...

Devdeep you are making same mistake that i committed.Here tank is already full and pumping doesn't mean just putting more water as it indicates both direction movement of water.So if you are pumping it can mean either filling or emptying the tank .
I committed same mistake.
 
@darth, @Shantanu.Kumar, Thanks Guys!!! I actually figured that right after posting my comment and hence edited it... Thanks again...

But the question says: "If 100 gallons of fuel are to be pumped into each tank," God!!! the INTO got me! :P
 
This time I will post one for kadeer.....

A + b/c ÷ d/e
If any of the above variables are to be doubled to halve the equation, which one should it be?

See, this question took me about 3 minutes to figure out. There's got to be an easier way to save time.

I just plugged in numbers..... what numbers did you plug in to get E as answer??
 
This time I will post one for kadeer.....

A + b/c ÷ d/e
If any of the above variables are to be doubled to halve the equation, which one should it be?

See, this question took me about 3 minutes to figure out. There's got to be an easier way to save time.

I just plugged in numbers..... what numbers did you plug in to get E as answer??

My mistake. I meant the answer was D not E.
 
What'd you guys think about the Khan Academy as a tool to brush up some stuff that I'm weak in?
 
Kadeer D can't be the answer either.
Actually you can't really double just one variable and half the equation.There is no solution to your problem.
his question was wrong. he forgot to include the paranthesis. d is definitely the answer. if the question is not correct, then you cannot double any variable to halve the equation
 
the actual gre is much easier. you are better off taking the ETS test from their website. it gives a better indicator of where you are. i remember taking the test the day before the exam and got all correct
 
Which of the following could be an area of an isosceles triangle if the perimeter is 18 and one side is 8?

a) 6
b) 12
c) 14
d) 16
e) 18

OK, sounds easy enough. Perimeter = a + b+ 8 = 18 thus other two sides must equal 10 as its an isosceles.

8+2 =
5+5 =

Should be the only ones that work to give two equal sides (isosceles). But none work.

This book is crap!
 
Which of the following could be an area of an isosceles triangle if the perimeter is 18 and one side is 8?

a) 6
b) 12
c) 14
d) 16
e) 18

OK, sounds easy enough. Perimeter = a + b+ 8 = 18 thus other two sides must equal 10 as its an isosceles.

8+2 =
5+5 =

Should be the only ones that work to give two equal sides (isosceles). But none work.

This book is crap!

If the sides are 8,5,5 the area turns out to be 12 (using hero's formula) and if they are 8,8,2 the area 3*sqrt(7) . Hence the answer is (b)
 
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